Drain plumbing for Steam Shower

(Posted this in General plumbing, and then realized it should be in this forum instead so I am reposting it here.)

I am doing a shower remodel, ripping out a bathtub and shower and replacing with a larger shower including a steam generator. I am DIY'er with some limited plumbing experience but little 'code knowledge'.

The p-trap in the foreground is for a 2" shower drain, and the smaller p-trap towards the back is for the drain line from the steam generator. The drain line coming out of the steam generator will be 1/2" copper, and at some point it will 'elbow down' into this drain. The generator is equipped with auto-flush, which means that after every use of the generator (and after a two hour wait for the water temp to cool down) the auto flush valve will open and drain the tank. This same drain line will be connected to the drain pan that the generator sits in.

In the picture, I simply laid a copper pipe with elbow above it on the footer for demonstration.

First of all, does this setup look okay? I have had someone question whether the venting is adequate?

Also, as to how to tie the copper drain line into the abs drain assembly in the background, I was thinking I could either extend the p-trap a couple more inches so it sits directly under the footer, then drill a hole through the footer and extend the copper right through so it sits just above the abs pipe and drains in, OR...

I could extend the p-trap laterally a few more inches so it sits under the closet floor next to the steam generator (see the hole in the sheetrock, that leads to my closet where the steam generator will be located) and then either install an actual floor drain or just have the abs come up through the floor here and 'hover' the copper pipe 3/4" above it.

(In case it's not obvious, there is a constant gradual slope from the shower drain, 'round the bend, and all the way along until it drops into the floor.)

This issue of flushing the steam generators is a tough one to work out. The only company that really has this figured out is ThermaSol. Consider switching your generator to this model and limiting the amount of plumbing work needed to be done.

I would worry about splash out from the configuration you have there.

It would be better to have the copper to ABS connection above the floor grade and done with some kind of copper to abs fitting like a few reducers and MPT FPT fittings. I'm assuming the flush cycle is with cold water only.

What I like so much about the ThermaSol flushing is that it is automatic and flushes through the showers steam head. This draining and extra plumbing work for a flush cycle not needed.

Good luck.

Looking forward to seeing it come together.

What approach to vapour management are you taking?

Noble Seal TS is our favourite but you can go many routes.

Is that vent "Dry" or does the sink use this line some how?

Click to expand...

John,

I have been told that (per code) the copper has to have 3/4" space between the bottom of the copper elbow and the top of the drain line. I would personally prefer a solid tie in like you mentioned, but I'm trying to be as close to code as possible.

In my understanding the 'auto-flush' is more of an 'auto-drain' - simply draining the water in the tank as opposed to actually flushing it out. The install manual says I can use the cold or hot water line for supply, but recommends the hot. I'm almost certain that draining out of the steam head is not an option with the Mr. Steam 225 that I have already purchased. It sure would make things easier if I could. But I will verify both of these things when I call Mr. Steam rep again today.

I'm using the Kerdi system for vapor (over the blue M-bloc board at HD, even though Kerdi actually says to use plain sheetrock), I believe that is what you're asking.

The vent in the picture goes four feet up into the wall and then joins a larger vent from the first floor of the house, laundry room and powder room are directly below)

Admittedly, I have a lot of things going on in this tiny space. Another option I could explore if this doesn't look right is to put a tee over the drain where it drops into the floor, and then use the right side for the shower drain (it would still have to make a 180 turn for the drain placement I want) and use the left side for the steam gen drain. With that setup, I could probably vent both sides after p-traps but before the 'drain drop'.

quote; If the line had a solid connection any stoppage in the drain line could put sewerage into the steam generator.

Exactly. At least with this configuration, all that will happen is that the steam "P" trap will overflow and flood the lower level of the building, but at least the shower will not fill with water. The shower drain is very convoluted and I might had tried to install a "neater" system.

From the vertical pipe coming out of the floor.....use a wye and catch the shower. Continue to the wall and turn up the wall. Now in the vertical stack install a sanitary tee and p-trap for the steam drains. You would be wet venting the shower and thats fine. Raise the steam generator so your line will have gravity fall to the trap. Its that easy.

Try somthing like this. Your steam unit will need to be elevated. the p-trap for it would be above the floor. I'm not trying to say you should use every fitting that i have pictured here. This is just an example to show how everything is vented.

Thanks for the visual, and all of the suggestions. I am still playing with a way to keep this all (or most) inside the joists because I dont have any room to spare in the closet to raise up the generator more than about 4 inches inside the closet. If I get anything that looks workable, I'll submit a new picture for further critique.

As for the Noble TS suggestion, the Kerdi cult got to me first, and I will probably stick with that system as I have already purchased all of the membrane and the drain kit.

My first concern with this is the distance that the vent line has to travel laterally before making the rise. It tavels 6'6" of horizontal distance, with enough space to rise vertically about 6" over that run. Is this enough of a slope for the vent? The vent I would use off to the right used to serve the old shower, and I had capped it off thinking I wouldn't need it. It is not tied to anything else, and goes straight up to the roof after that run of 6'6"

The other vent line in the wall on the left that will vent the steam gen drain line was previously used to vent the bathtub drain. The bath was ripped out and this is where the shower will be now. This vent line rises inside the wall to the left and about four feet up it joins the larger 2" vent pipe you can see at the very bottom of the picture.

As for the steam generator drain, I would like to extend it another foot to the left so the trap lies beneath the subfloor in the closet, and then have the riser come up through the floor where it will meet the drain line from the gen.